PDCD1 and serous adenocarcinoma: In gynecologic cancers, EC showed the highest overexpression of programmed cell death 1 (PD-1, CD279) and programmed cell death ligand 1 (PD-L1, CD274): 40–80% in endometrioid carcinoma, Serous carcinomas accounted for 10–68% of tumors, and clear cell tumors accounted for 23–69%, respectively [36].